Insulin can be visualized as acting in two sites, viz, the site of production of glucose (liver), and the site of utilization of glucose (peripheral muscle, adipose tissue, etc). In normal man, it is thought that the primary site of glucose regulation is at the liver, suppressing glucose production. In Type I diabetes (insulin dependent), the usual replacement of insulin via the subcutaneous tissue (shots) exposes the periphery to insulin thereby enhancing glucose utilization. The liver in this situation is under-insulinized.